<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            padding: 0;
            margin: 0;
        }

        .adBox {
            width: 300px;
            height: 400px;
            background-color: #6ff;
            position: fixed;
            right: 5px;
            bottom: 5px;
            display: none;

        }

        .title {
            position: relative;
            font-size: 14px;
        }

        .title .tips {
            text-indent: 5px;
        }

        .title .close {
            position: absolute;
            right: 0;
            top: 0;
            padding: 0 4px;
            background-color: #f00;
        }

        .body img {
            width: 100%;
        }
    </style>
</head>

<body>
    <div class="adBox">
        <div class="title">
            <div class="tips">距离广告关闭还有8秒</div>
            <div class="close">x</div>
        </div>
        <div class="body">
            <a href="">
                <img src="https://img20.360buyimg.com/babel/s580x740_jfs/t1/169223/11/9002/236742/603f38feEa4a8d83e/4ace79eafcac855c.jpg!cc_290x370.webp"
                    alt="">
            </a>
        </div>
    </div>
</body>
<script>
    var adBox = document.getElementsByClassName("adBox")[0];
    var tips = document.getElementsByClassName("tips")[0];

    setTimeout(function () {
        adBox.style.display = "block";
        var num = 8;
        var timer = setInterval(function () {
            num--;
            tips.innerText = `距离广告关闭还有${num}秒`;

            if (num == 0) {
                clearInterval(timer);
                adBox.style.display = "none";
            }

        }, 1000);

    }, 1500);
</script>

</html>